Sink



FIG. 1 is a front perspective view of a sink in accordance with the present design;

FIG. 2 is a front elevational view thereof;

FIG. 3 is a top plan view thereof;

FIG. 4 is a bottom plan view thereof;

FIG. 5 is a right end view thereof; and,

FIG. 6 is a left end view thereof.

The broken lines shown are included for the purpose of illustrating a portion of the sink that form no part of the claimed design. 

CLAIM The ornamental design for a sink, as shown and described. 